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The simulation and teaching methods described in the papers, posters, and presentations on this page cover a range of topics, including: implementing features and interfaces for specific applications, sharing practices and experiment techniques, and the use of certain mathematics and models in the software.

Geometries with heterogeneous material properties are typically defined as a set of multiple parts, each part representing a different material. However, assembling or defining the individual parts of complex geometries can be difficult. A practical method based on image-based mesh generation, a custom algorithm for labeling materials, and interpolation functions of COMSOL Multiphysics® can be used to mesh complex geometries and to assign heterogeneous material properties without the challenge of assembling multiple parts. A case study demonstrates how the method was used to mesh a chicken carcass and to define the material properties of the meat, bones, and internal cavity sections without the need of assembling. The resulting mesh was used in a model to simulate air-cooling of poultry carcasses.

Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore

This presentation gives an account of how COMSOL Multiphysics® software has helped to accelerate research and development. It has been used to simulate energy systems such as fuel cells, biomedical systems such as hydrogels and human skin, and monolithic catalytic converters. Each of these systems requires a mathematical model that can accurately represent the relevant physics, and which can be solved without prohibitive computational cost or unreasonable setup. In each case, COMSOL has met all three of these needs.

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COMSOL results showing the streamwise velocity distribution in the channels in the monolithic catalytic converter

This paper describes COMSOL Multiphysics® simulations of the stress and crack development in the area where a masonry wall supports a floor. In these simulations one of the main material properties of calcium silicate, its E-value, was assigned randomly to the finite elements of the modeled specimen. Calcium silicate is a frequently used building material with a relatively brittle fracture characteristic. and its initial E-value varies, as well as tensile strength and post peak behavior vary. Therefore, in the simulation, initial E-values were randomly assigned to the elements of the model and a step function used for describing the descending branch. The method also allows for variation in strength to be taken into account in future research. The performed non-linear simulation results are compared with experimental findings. They show the effects of varying material properties on stress distribution and cracking behavior in point loaded masonry.

This paper presents information on techniques needed in COMSOL Multiphysics® to enable computational studies of coupled systems of PDEs for time-dependent non-linear problems. Furthermore, we demonstrate how to use data files as input for initial conditions. To illustrate the techniques, we consider a system of two time-dependent non-linear PDEs from mathematical biology that couples an excitation variable and a recovery variable. This physiological process is characterized by the visual appearance of a double spiral wave, a reaction-diffusion wave of the excitation variable that moves through the domain in a spiraling, recurrent curl pattern.

Pressure Sensors are widely used in the automotive industry. Their main use is the dynamic monitoring of pressure inside combustion engines. To achieve a good signal accuracy, the design of pressure sensors can be improved with FEM calculations of stress and strains on the measuring cell depending on their geometry and material properties.
The geometry is adapted according to a special nominal pressure and a limit rule of the stresses. The non-linearity can be calculated conforming a use of strain-gages over the membrane surface.
The design with FEM tools allows us to analyze tolerances in the geometry, their effects on the signal and mechanical stability of the sensor.

Energy harvesting from ambient vibrations has become an interesting topic for powering wireless sensor networks. Resonant microdevices based on MEMS have become of central importance at low frequency. The power produced at resonance is at least one order of magnitude larger than off frequency power since the largest strain is obtained at resonance. In order to obtain large strain for efficient electromechanical energy conversion, polymer materials have been considered for vibrating devices. Two preliminary resonant microcantilevers made of viscoelastic polymer have been simulated with COMSOL Multiphysics® to deduce both the resonant frequency and quality factor. We have also investigated how the resonant frequency and the axial strain vary with the microcantilever thickness, to optimize the behavior of such MEMS resonators as electromechanical energy harvesters.

The objective of this study was to develop an easy to use interface in Excel® that connects to not only the solvers in COMSOL Multiphysics®, but also existing databases of food properties, foodborne pathogenic microorganisms kinetics, and chemical kinetics, creating a comprehensive simulation software to predict food safety and quality. The user interface allows the user to select the food, pathogen, and chemical name and then press a visual basic application (VBA) macro button that retrieves the food properties and kinetic equations for the user. Effective transport properties are automatically calculated for the user inside COMSOL. The extension of macros significantly improves the data retrieval process, instead of the laborious task of searching through databases for values and calculating transport properties.

University of Salerno, Department of Industrial Engineering, Fisciano (SA), Italy

Aim of the study is to determine the influence of some of the most important operating variables, especially humidity and temperature, of drying air on the performance of cooking process of pork meat. The process is simulated using finite elements software COMSOL Multiphysics®. The proposed model considers two geometries: cylindrical and parallelepiped, with fixed physical properties and convective boundary conditions. The model was used to predict transient temperature and moisture distributions inside the product, as well as transient cooking yield of meat samples during cooking. It is expected in the future to create a model for cooking pork meat in a microwave oven and compare it with the results obtained for the classical convection oven.

Circuit board failures are often ignored because they could be impreceptible. This simulation examines how internal layers around a soldered pin via subject to temperature changes during the soldering process are affected, show the forces involved and determine breaking points.
A 2D thermo-mechanical model of a soldered pin is achieved in two simulation steps. First, a connecting pin already attached to a fixed circuit board is placed in the via of a secondary circuit board, both are heated to a temperature according to the soldering process, then as a second step, the tin-solder is placed between the pin and secondary circuit board to finally let the system cool down.

Electrostrictive polymers have been of significant interest over the last years for energy harvesting. Principle is based on the conversion of a mechanical deformation into electricity. The stored energy basically depends on the mechanical strain induced into an electrostrictive polymer by the mechanical resonant vibration of a microcantilever supporting the electrostrictive layer. In this work, in order to obtain large strains, polymer materials, which have small Young’s modulus, have been considered for the vibrating microcantilever. However the drawbacks of such materials are their viscoelastic properties which cause the major losses of the vibrating system. In this paper, microcantilever made of viscoelastic polymers is simulated with COMSOL Multiphysics® using two different vibration methods to deduce the losses in the system and then the quality factor, which is an important parameter for the energy harvester design.

The conductivity of seawater directly correlates with the concentration of dissolved salts. This model demonstrates a new approach to the methodology of inductive conductivity measurement of seawater and other liquids. COMSOL Multiphysics® was used to build a parametrically swept model of an O-Core Inductive Conductivity Measurement Sensor for Seawater. This sensor model is built using the Magnetic Fields (mf) and the Electric Circuits (cir) physics interfaces. The model employs is a dual multi-turn coil O-core inductive conductivity measurement sensor. Multiple turns of copper comprise the primary coil. Multiple turns of seawater comprise the secondary coil. The calculated family of secondary coil currents demonstrates that the secondary coil current changes directly with secondary (seawater) coil conductivity.

A sharp tip approached perpendicular to a conducting surface at subnanometer distances and biased with a small voltage builds a junction across which electrons can be transferred from the tip apex to the nearest surface atom by direct quantum mechanical tunneling. Such a junction is used e.g. in Scanning Tunneling Microscopy (STM).
When the distance d between tip and collector is increased beyond some nanometers, the junction enters the electric field assisted regime, the one underlying the topografiner technology –an imaging technique widely used in micro- and nano-electronics. Recent experiments in this regime suggest a scaling law which can be tested numerically by verifying the collapsing of a family of
electric potential curves, computed at different d, onto one single curve.

Moisture can cause serious damages in different building components therefore the heat and moisture calculation in building constructions are important tasks. In the current paper, two different multi-layered walls, mainly consisted of wooden materials and mineral wool, are analyzed. Risks of mould growth under Latvian climate conditions are estimated using 3 different approaches: experimental results in real test houses, commercial software WUFI®PLUS for simultaneous heat and moisture transfer in 3D buildings and COMSOL Multiphysics® for 1D case. Results obtained from this 3 approaches are compared. It is shown that calculations with COMSOL Multiphysics® give good fitting with experimental results.

Multigrid methods (MG) belong to the fastest solvers for partial differential equations. The key for this is an appropriate composition of the algorithmic components [1,2,4]. The multigrid solver implemented in COMSOL Multiphysics® is analyzed with respect to components and with respect to its numerical properties. Of special interest is the question whether solving selected model problems shows that behavior which is known from multigrid theory.
COMSOL Multiphysics® allows the composition of time-, convergence-, and memory-efficient MG algorithms both for model problems and concrete applications which work in the range predicted by theory and known by experience.

The Large Eddy Simulation is an important method to simulate turbulent flow. It does not produce a closed system of equations, to achieve this it is necessary to model the not-closed terms. The deconvolution can be used for this purpose. In this study some numerical experiments on this topic are performed with COMSOL Multiphysics®. The main objectives are to find an efficient way to implement deconvolution and to evaluate its numerical behavior, with particular attention to the boundary conditions, or rather to their LES-deconvolution modeling.

We report an implementation of parallel computing on Amazon Web Services™ (AWS) for touch-sensor modeling. COMSOL Multiphysics® was used to simulate an electromagnetic field distribution in a capacitive sensor assembly. Multiple COMSOL jobs were deployed on separate AWS instances and were executed in parallel. The simulation results indicate that implementation of parallel computing for COMSOL simulations can significantly reduce the computational time required for optimization of capacitive touch sensor patterns.

1National University of Engineering, Lima, Perú2Polytechnic University of Madrid, Madrid, Spain

We formulate a new mathematical model of gas-solids mixing hydrodynamic flow [1] in a combustion chamber with a fluid bed system used in the combustion of mineral coal waste. This model in study is called Model Gas-Solids Mixing and it is constructed by averaging the conservation equations (mass and momentum) for a two-phase flow, which takes into account the existence of a small parameter rho in the order of 10 ^ (-4). This parameter is related to the ratio of the mass densities of both phases and is a free boundary problem making an asymptotic adjustment in the model. This model is important in the production of thermal energy-based solid waste. The simulation is implemented in COMSOL Multiphysics®.

Nowadays all branches in modern science and industry tend to solve ever complicating problems. As the result the computational time increases considerably and it become very important to reduce the processing time and use available resources more efficiently. Parallelizing problem proves itself as efficient way to overcome the described problem. In the poster we compare different methods of parallelization and show what can work the best for COMSOL Multiphysics® software.

Morphogenesis is a tightly regulated process that has been studied for decades. Previously we developed data-based mechanistic models for a range of developmental processes with a view to integrate the available knowledge and to better understand the underlying regulatory logic. In our previous papers on simulating organogenesis in COMSOL Multiphysics® we discussed methods to efficiently solve such models on static and growing domains. Another challenge in modeling morphogenesis is the parameterization of the models. Here we discuss COMSOL-based methods for parameter optimization. These routines can be used to determine parameter sets, for which the simulations reproduce experimental data and constraints. Such data is often image based, but may also come from classical biochemical or genetic experiments.

This paper deals with an integrated numerical and experimental analysis work aiming at the investigation of the thermal stress on nanowires in electronic gadgets especially computers and mobile phones. The comparative study of the nanowires are analyzed through the Thermal Stress physics using different variants such as Cu, Al, ZnO, Si(c), SiO2 which can be used in sensors, solar cells, LCD, batteries. The main goal of the research is to find effect of nanowire dimensions related to thermal stress developed by the gadgets. During the experimental measurements, three different combinations of materials are used to design a nano probe that can indicate the temperature increase on the surface of gadgets. In this study, the deformation in the nanowires due to thermal variations produced by the gadgets is simulated using COMSOL Multiphysics®.

The effects of sharp corners on the flux distribution in a ferromagnetic core are modeled using COMSOL Multiphysics® to determine the time-domain flux density for an applied field which is uniform in the non-corner section of the core. The frequency spectrum of the flux distribution is calculated for testing points through the corner and the effects of harmonic frequencies on the flux and loss profiles are analyzed. The contribution of higher-order harmonics is presented and shown to contribute up to 3.8% of the total loss in the areas of the core where the flux enhancement is highest. Flux reduction is also considered in the outer edges of the core and shown to be dependent on harmonic frequencies in the flux profile.

LiveLink™ for MATLAB® is used to fit the surface temperature of a battery cell within a COMSOL Multiphysics® model to the temperature measured by a thermal imaging camera.
The test bench was designed and built up of ourselves to allow nondestructive thermal diffusivity measurement of Li Ion cells as a function of temperature, state of charge (SOC), state of health (SOH) and others. In that way we determined the through-plane thermal diffusivity of Pouch cells in transmittance setup and the radial component of Cylindrical cells in reflective setup. Although the cell housing is ignored, the measurement can be fitted rather accurate by the models.
With a corresponding COMSOL Multiphysics® model, even the in-plane values of Pouch cells, respectively axial parameters of Cylindrical cells, can be determined using this approach.

Undergraduate studies are carried out to examine the supersonic flow from an axisymmetric converging-diverging nozzle. Flow in the nozzle is initiated by the rupture of a diaphragm that is positioned between the nozzle and a 1-gallon pressurized air tank. Simulations are carried out in COMSOL Multiphysics® for unsteady, axisymmetric flow with the High Mach Number interface of the CFD Module. Adaptive meshing is utilized to capture the structure of the flow, including the initial shock wave and the Mach diamonds that are present after the flow from the nozzle has been fully established. Qualitative and quantitative comparisons are made to the COMSOL simulation with experiments based on high-speed video shadowgraph imaging and dual-beam interferometry measurements.

A numerical model was developed to make spatial and temporal predictions of the water quality for Brewster Lake, located in southwestern Michigan. The model considers the hydrodynamics of the lake, hydrologic conditions, physical, chemical and biochemical processes that take place in the lake, and nutrient loadings from the surrounding watershed. Physical, chemical, and biochemical data collected was used to establish appropriate initial and boundary conditions. In addition, hydrologic data for the region was obtained from three nearby weather stations. COMSOL Multiphysics® was used to solve the resulting integrated complex numerical model and to develop a 2-D graphical model of the lake. The EPA WASP7 water quality simulation program was then used to compare predictions of the different water quality parameters.